it means that if the female that you are about to have intercourse with is menstruating you could alternativly penetrate her Anal regions with your Penis.what does that even mean?!
How do you know when you've run out of invisible ink ?
You can make invisible ink out of milk or lemon juice
Hold a flame up to the paper (obviously don't set the paper alight) and the writing will be revealed.
I heard semen worked aswell, but not tested it, anyone know?